1. Field of the Invention
The present invention relates to a method for imaging and measuring the heat flux distribution on an object surface, and to a heat flux distribution imaging and measurement system suitable for measuring the heat flux distribution on the body surface of a thermodynamic apparatus, commonly a rocket or an aircraft, by means of this method.
2. Description of the Related Art
In conventional practice, several measurement methods have been reported as imaging and measurement techniques for calculating heat fluxes using temperature-sensitive paint. For example, the techniques disclosed in nonpatent reference 1 (J. P. Hubner, et al., “Heat-Transfer Measurements in Hypersonic Flow Using Luminescent Coating Techniques,” Journal of Thermophysics and Heat Transfer, Vol. 16, No. 4, 2002) and nonpatent reference 2 (T. Liu, et al., “Heat Transfer Measurement on a Waverider at Mach 10 Using Fluorescent Paint,” Journal of Thermophysics and Heat Transfer, Vol. 9, No. 4, 1995) entail applying a temperature-sensitive paint to an object surface and detecting its emission thereof to calculate the heat flux, but limitations are imposed by these techniques on the calculation of the heat flux. For example, nonpatent reference 1 offers two types of analysis techniques. At first method, the emission intensity and heat flux in an image are correlated using an in-situ method, and at the second method, a calculation is made the assumption of the steady heat flux. The in-situ method is one in which calibration characteristics are obtained while experiments are performed, and, according to this reference, the calibration characteristics are calculated upon finding a correlation between the intensity of emission from a temperature-sensitive paint and data from a number of heat flux sensors mounted on an object surface, which is the measurement object. A calculation performed on the assumption of the steady a heat flux cannot be applied to randomly varying phenomena because this approach is not valid for phenomena in which the heat flux varies over time. According to nonpatent reference 2, a heat flux is calculated on the assumption of steady heat conduction, but this methods has limitations in terms of its applicability to unsteady phenomena or short-duration phenomena.
Methods in which the measurement object is made of ceramics, and thermographic phosphors are admixed into the ceramics or an infrared camera is used are cited as techniques using materials other than temperature-sensitive paints. These methods are described, for example, in nonpatent reference 3 (G. M. Buck, “Simultaneous Global Pressure and Temperature Measurement Technique for Hypersonic Wind Tunnels,” AIAA 2000-2649, 2000) and nonpatent reference 4 (Tadao Koyama, Shoichi Tsuda, “Aerodynamic Heating Measurement by Infrared Thermography,” Journal of the Visualization Society of Japan, Vol. 19, No. 75 (October 1999)). According to nonpatent reference 3, the measurement objects are limited to ceramics, making this method inapplicable to objects that comprise arbitrary materials. In addition, the method of nonpatent reference 4 is substantially difficult to apply to metals or other low-emissivity materials. Furthermore, both nonpatent reference 3 and nonpatent reference 4 describe calculations performed on the assumption of the steady the heat flux, and are thus inapplicable to unsteady phenomena.